31,
This brings up the subtle meaning of the word Adventitious root fibers. These are the roots that occur from buds and not from a woody stem,etc. I don't think these roots from the picture are formed as a part of Apomixis as in stem cuttings such as the means of rooting cacti and other such processes. If anything, it can be similar to stress rooting.
I will not bring up Pneumataphoric root formation...!!!!